Johannesburg, South Africa (CNN) -- Another powerful union in South Africa is threatening to join the massive strike that has already crippled the country.
The National Union of Mineworkers said Friday it will join the public sector strike next week if the government does not meet the demands of strikers who want more money.
"We are angry that whilst those who are privileged have children go to school overseas; our children have turned into street kids," the union said in a statement.
"The NUM fully supports the public sector strike and would next week Thursday ensure that every mining operation, every construction site and every energy worker joins the public sector strike in different forms."
The mineworkers union is the largest union in the Congress of South African Trade Unions, the group says.
Industrial unrest has hit South Africa several times during the past few weeks as striking public sector workers have halted services across the country, including at schools and hospitals.
Employees have called for wage rises of more than eight percent -- well above inflation -- and enhanced housing allowances as part of their demands.
But the government says it cannot afford to meet workers' demands and has ordered military doctors and nurses into dozens of hospitals to protect vulnerable members of society.
Public sector wages make up a third of South African government spending. Unemployment stands at 25 percent.
Striking workers have rallied in South Africa's main cities and towns, including the capital Pretoria, Cape Town, Johannesburg, Limpopo, KwaZulu Natal and the North West Province among others.
CNN's Kim Norgaard and Robyn Curnow contributed to this report.